A simple Ar / CO2 gas mixture system was setup by Bob Soja and Carter Biggs. A picture is shown here with the CO2 flow controler on the left and the Ar flow controler on the right. 

C02 flow rate level on Saturday, June 16, 2012 before adustment:

C02 flow rate level on Saturday, June 16, 2012 after adustment:

Ar flow rate level on Saturday, June 16, 2012:

The system did not work in a very stable manner. On Friday, June 15, 2012 the system was adjusted to provide 80/20 gas mixture. On Saturday, June 16, 2012, the C02 flow rate level changed. I adjusted the level back to where it was supposed to be to provide 80/20 gas mixture according to the technicians. The runs below were taken under those conditions. The accuracy of the actual attempted 80/20 gas mixture is at most a few percent.  During the runs taken over a 1h period, the gas flow rate was stable. 

A 2nd attempt was made on Monday, June 18, 2012. However, the CO2 gas flow rate was zero and could not be adjusted any longer. After a brief discussion with Bob Soja, it was decided to terminate this test.

Documentation of runs take during 80/20 gas mixture scan on Saturday, June 16, 2012: